Records of two ammonite species Pseudokossmaticeras pacificum (Stoliczka, 1866) and Brahmaites (Brahmaites) mikobokensis Collignon, 1971, from the St Lucia Formation of northern KwaZulu-Natal are dated as Late Maastrichtian on the basis of associated inoceramid faunas. These records suggest that the Madagascan 'Early' Maastrichtian 'Zone ä Pachydiscus neubergicus et Pachydiscus goííeviííensis', in which these species also occur, is in part Late Maastichtian.

The present note complements our revision of the Kossmaticeratidae from KwaZulu-Natal and Eastern Cape Province (Kennedy & Klinger, 1985) with records of two additional species. Pseudokossmaticeras pacificum (Stoliczka, 1866) was originally described from South India, and subsequently recorded from Madagascar (Collignon, 1938, p. 104, pl. 8, fig. 5; 1971, p. 38, pl. 647, fig. 2398; pl. 655, fig. 2418). Brahmaites (Brahmaites) mikobokensis Collignon, 1971 was previously known only from Madagascar. The interest of the present records is the light they shed on the age of both taxa. The occurrence of P. pacificum in South India is not precisely dated. In Madagascar, both species were recorded by Collignon (1971) from his Zone à Pachydiscus neubergicus et Pachydiscus gollevillensis, which he attributed to the Lower Maastrichtian. But the fauna of the zone contains many taxa that are exclusively Late Maastrichtian in western Europe and elsewhere, Pachydisus gollevillensis (d'Orbigny, 1850), P. jacquoti (Seunes, 1890), and Menuites fresvillensis (Seunes, 1890), typical of the lower Upper Maastrichtian fresvillensis Zone in the expanded Biscay sections (Ward & Kennedy, 1993). However, this zone is in fact upper Lower and lower Upper Maastrichtian in Ward & Kennedy 1993, e.g. fig. 14; gollevillensis, jaquoti and fresvillensis range into the lower Maastrichtian in the same figure. That the present species are of Late Maastrichtian age is confirmed by the associated inoceramids (see revision in Walaszczyk, Kennedy & Klinger, 2009). These document that P. pacificum occurs in association with the late Early and early Late Maastrichtian Trochoceramus radiosus assemblage, and B.(B.) mikobokensis with the late Early Maastrichtian 'Inoceramus' ianjonaensis assemblage. However, in Walaszczyk et al. (2009) the radiosus assemblage was assigned to Lower Maastrichtian and ianjonaensis to the Upper Maastrichtian. In Walaszczyk et al. (2010, fig. 1) the T. radiosus zone spans the Lower/ Upper Maastrichtian boundary. We conclude that the Madagascan Zone ä Pachydiscus neubergicus et Pachydiscus gollevillensis is in part at least Late Maastrichtian, given that P. (P.) neubergicus ranges into the Upper Maastrichtian in the Biscay sections (Ward & Kennedy, 1993, fig. 14).

The lectotype, here designated, is the original ofStoliczka (1866, p. 160, pl. 77, fig. 9), from the Arrialoor Group of Vencataramapooram, South India. There are also two para-lectotypes, from north of Camarapolitam.

SAM-PCZ22195 is a well-preserved composite mould with an estimated maximum preserved diameter of 70 mm. Coiling is very evolute, the shallow umbilicus comprising an estimated 50% of the diameter, the umbilical wall low, and broadly convex, the umbilical shoulder narrowly rounded. The whorl section is compressed reniform, the whorl breadth to height ratio 0.9, with the greatest breadth just outside the umbilical shoulder. The flanks are feebly convex, convergent, the ventrolateral shoulders broadly rounded, and the venter very feebly convex. The adapertural 60° sector of the penultimate whorl bears 12 ribs, most of them narrow, weak, straight, prorsiradiate primaries that weaken and efface over the venter. Two develop a feeble umbilical bulla. There is a single narrow, prorsiradiate constriction. It is preceded by a strong, bullate collar rib, and succeeded bya much weaker rib that lacks a bulla. The preceding, adapical section of whorl is only partially exposed, with a single constriction and several bullate primary ribs. An approximately 120° sector of body chamber is preserved, with a maximum whorl height of 23.4 mm. Eighteen ribs are preserved on the fragment. All but one of the ribs are primaries. They arise at the umbilical seam and strengthen across the umbilical wall. They are straight and recti- to feebly prorsiradiate across the flanks, strengthening progressively, and passing straight across the venter where they reach their maximum strength. At the adapical end of the fragment the very regular ribbing is interrupted by a constriction that is flanked by simple ribs, the adapical one stronger than the adapertural one. The adapical collar rib is preceded by a single short intercalated rib.

Discussion

The ornament of the inner whorls matches well with the smaller lectotype, which has a maximum preserved diameter of an estimated 55 mm. It does not develop the coarser ribbing of the larger, adapertural sector of the outer whorl of the present specimen. The specimen from Ianjona, Madagascar, described and figured by Collignon (1938, p. 104, pl. 8, fig. 5) is 54 mm in diameter, shows a comparable change from finely ribbed inner, to progressively coarsening outer whorl, but not reaching the degree ofcoarseness developed by the present, larger specimen. Cooper (1989, p. 252, fig. 1a,b) figured a poorly preserved fragment from the same locality as the present specimen.

The holotype, by original designation is the original of Collignon (1971, p. 22, pl. 648, fig. 2400, from 'Gisement 496-D, Ianjona-Ouest-Mikoboka (Manera), Madagascar', housed in the collections of the Université de Bourgogne, Dijon. It is reillustrated here as Fig. 2.

Material

SAM-PCZ22196, from the Maastrichtian St Lucia Formation, of locality 20 of Klinger & Kennedy, 1975 (p. 283), the cliff section at the junction of the old course of the Mfolozi, the present river, and an unnamed stream draining south from Lake Mfuthululu, ESE of Mtubatuba, coordinates: 28°26'59"S, 32°16'36"E. A fragment, OUM KX9098, is from locality 134 of Kennedy & Klinger (1975, p. 298), foreshore outcrops in Makakatana Bay, east of the village, 28°13'51"S, 32°25'08"E.

Dimensions

Description

SAM-PCZ22196 is a composite mould of a phragmocone 94.6 mm in diameter. Coiling is very evolute, the broad umbilicus comprising 50% of the diameter. The umbilicus is shallow, with a flattened, outward-inclined umbilical wall. The umbilical shoulder is narrowly rounded, the whorl section depressed reniform, with the greatest breadth at the umbilical shoulder. The whorl breadth to height ratio is 1.25. The flanks, ventrolateral shoulders and venter are broadly and evenly rounded. There are more than 40 narrow, blunt, crowded ribs that are well-developed on the ventrolateral shoulder, sweep forwards across the inner flanks, weaken progressively, and are effaced on the ventrolateral shoulders and venter. There are sixprominent prorsiradiate constrictions on the outer whorl. They sweep forwards across the flanks, and cross the ventrolateral shoulders in a broad convexity. They are interrupted at mid-venter by a narrow groove, corresponding to a low ridge on the interior of the shell, presumably marking the site of attachment of the ventral muscle. The suture is very deeply and intricately incised, the saddle E/A bifid with a very narrow, deeply dissected stem, a narrow and trifid A, and A/U2 only slightly smaller than E/A.

Kennedy acknowledges the support of the staff of the Geological Collections, Oxford University Museum of Natural History, and the Department of Earth Sciences, Oxford, and the financial assistance of the Oppenheimer Fund (Oxford). Klinger acknowledges the technical support from the staff of the Natural History Collections Department, Iziko South African Museum and financial support of the NRF, South Africa.